The present application is a continuation-in-part of U.S. patent application Ser. No. 10/146,275, filed May 15, 2002 and U. S. patent application Ser. No. 10/136,171, filed May 1, 2002 now U.S. Pat. No. 6,929,767.
The present invention relates to an open mold manufacturing process, and more particularly to a manufacturing process which generates a process airflow which maintains auto fire in a regenerative thermal oxidizer.
Open mold fiberglass reinforced plastic molding systems are well known. Molds travel once along an assembly line. A plurality of operations are performed at stations along the assembly line until a finished part is removed from the mold at the end of the assembly line.
Multiple stations along the assembly line are spray stations. As the molds transit the spray station a particular spraying operation is performed. Such spray operations include gelcoat and resin/catalyst/chopped fiberglass fixture application. Multiple coats are often required for one or more spraying operations necessitating additional spray stations. Stringent environmental regulations apply to these spraying operations as the sprayed material involves several chemical reactions. Conventional spray stations provide an open environment in which an airflow is directed from behind a spray operator to direct mold overspray into an exhaust port.
Environmental regulations are becoming more and more inflexible. The expense of providing environmental emission control devices which meet environmental regulations often results in cost prohibitive manufacturing facilities. Often older facilities become non-compliant and must be idled. The expense of the regulation may be particularly high for an assembly line type molding system as spraying occurs at multiple locations along the assembly line. The entire facility is therefore typically subjected to particularly harsh environmental regulations.
Assembly line type molding systems require a rather large manufacturing facility footprint as a curing station typically follows each spraying station. The sequential nature of the assembly line environment provides for constant movement of the molds. The curing stations must be of a length to assure proper curing of the prior spray operation. Multiple lengthy curing stations greatly lengthens the assembly line. A larger manufacturing facility is subject to harsher environmental regulations than a smaller facility.
The sequential nature of the assembly line environment provides multiple spray stations spaced along its length. Each spray station is vulnerable to many exogenous variables that are difficult to control in a cost effective manner. Control of these variables is only magnified in larger manufacturing facilities.
Typically, human operators at each spray station are highly trained to minimize volatility in the manufacturing process. Many individual operators, even though highly trained, still may create manufacturing process volatilities due to variance in human technique and process manipulation. Robotic sprayers are often provided in place of operators to increase spraying consistency. However, this may simply result in many robotic spray stations replacing many human spray stations without a substantial reduction in expense.
Moreover, conventional molding systems provide a low concentration of heat producing HAPs (Hazardous Air Pollutants) and VOC's (Volatile Organic Compounds) in combination within rather high process airflow. Due to the low concentration high airflow, auto fire within the environmental control system is not readily achieved. Auxiliary fuel gas such as natural gas must be added to the process airflow to supplement the air pollutant concentrations such that operational temperature for the environmental burner system is maintained. The requirement for auxiliary fuel gas decreases efficiency and increases process costs.
Accordingly, it is desirable to provide an open mold manufacturing process which meets stringent environmental regulations within a small footprint facility. It is further desirable to minimize manufacturing process volatilities due to exogenous and human variables in a cost effective manner. It is still further desirable to generate a process airflow which maintains auto fire in environmental burner system.